In this video, Professor Martin Wooster explains the importance and some of the basic principles of EO validation activities. He demonstrates, through a recent field study, an example of how validation of satellite active fire detections and the energy released from fires can be conducted, in a collaboration with the Scientific Services of Kruger National Park (SANParks), South Africa.
Earth observation is an extremely effective way of monitoring the Earth system, but it does not directly measure most of the Earth system properties we are interested in. Instead, the value of the targeted property (for example sea surface temperature (SST)) at the observed ground location corresponding to the satellite image ‘pixel’ under analysis, must be estimated from the measurements of electromagnetic energy arriving at different wavelengths from the area covered by that pixel.
For example, SST is usually estimated from an analysis of the different remotely sensed signals arriving from an area in a series of closely spaced thermal infrared wavebands (one waveband covering a relatively narrow range of wavelengths). As a result of the somewhat ‘indirect’ nature of such remotely sensed estimates of SST, it is extremely important that they are checked for their accuracy and precision, to ensure they meet specification and so that users of the data can be reliably informed of the uncertainties that are present (e.g. ‘the SST is known at this location to within ± 0.5 °C at 95% confidence’). This is one part of making such datasets ultimately well-suited for climate-related studies, where often trends occurring over time must be differentiated from other signals that might be present in the data.
Validation of remotely sensed information is therefore considered extremely important, and is often performed as part of the process of generating a new data product from satellite remote sensing. Validation often involves comparing the remotely sensed estimates at a particular location to those obtained via a trustable and independent ground-based measuring technique, which already has a known certainty, and can also involve comparison of two different and independent satellite-based estimates of the same parameter, perhaps taken at different spatial resolutions or with different measurement approaches.Featured Educators:Additional on-screen contribution from Mark De Jong, King’s College London.Thanks to Scientific Services, Kruger National Park, SANParks and colleagues from King’s College London for enabling filming at the South African field tests.South Africa filming by Anna Turbelin.Explore the Imagery, Data and Satellites:
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